Bio Exam 3
What do spontaneous mutations result from?
abnormalities in cellular and other biological processes examples: loss of base on one strand or mismatch of base pairs
Why are older people more likely to have cancer?
accumulation of mutation in the development of a cancer cell take time
Why can't a plant cell pinch inward and form a cleavage furrow?
all plant cells are surrounded by a stiff cell wall that prevents pinching inward
Where do traits come from?
alleles of each gene --only one allele will usually determine on organisms appearance
What do the nuclear pores do?
allow things to go in and out of the cell (security)
What is a gastrula?
an embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells.
what is reproductive cloning?
an embryo produces through nuclear transplantation energy may develop into a new living individual
What are stem cells?
an embryo that was either naturally occurred or or produces via nuclear transplantation
What are frameshift mutations?
an insertion or deletion that alters the reading frame and often results in the production of a completely different (and defective) protein
What is the cell cycle?
an ordered sequence of events from the time a cell is created from a dividing parent cell until its own division into two cells
What does each chromosome consist of?
One very long molecule of DNA plus proteins that help organize and compact the DNA
What are lysosomes?
A type of vesicle (not involved with protein production) that contain digestive enzymes that can dissolve large food molecules, old cellular components, or invasive organisms like bacteria
What is the definition of a gene?
A unit of hereditary information consisting of a specific nucleotide sequence in DNA
How many proteins do humans have?
About 100,000
What two kinds of mutations exist?
Advantageous - lead to improvements in an organism; change makes the organism better suited to its environment Disadvantageous - harmful and will not enhance the survival of the affected organism
Explain the second step of transcription (RNA polymerase synthesizes a molecule of RNA)
After it binds at the promoter, RNA polymerase peels open the double helix of DNA, exposing the two strands. One strand serves as a template for the formation of RNA; the other DNA strand is unused. RNA polymerase moves down the DNA, creating a new RNA molecule one nucleotide at a time following base pairing rules (remember U replaces T). As RNA synthesis continues, the growing RNA strand falls away from the DNA, allowing the two separated DNA strands to rejoin in the region already transcribed.
Why is a metastatic cancer much harder to treat than a non-metastatic cancer?
After metastasis, the tumor has spread to multiple locations, making it much harder to treat with surgery or radiation
What's the relationship between small and large pieces of DNA regarding gel electrophoresis?
Smaller pieces of DNA migrate toward the bottom of the gel faster than the larger pieces
How are mutations caused?
Some occur spontaneously due to errors that occasionally (but rarely) happen during DNA replication. Other mutations are caused by mutagens
What are introns?
Stretches of the RNA that do not actually code for amino acids
What is an autosome?
The 44 nonsex chromosomes
During DNA profiling, are the sequences of the entire set of DNA in each sample compared?
No, DNA profiling techniques rely on comparing small regions of DNA
If you wish to compare DNA from a suspect and a crime scene, would you use PCR to duplicate the entire genome?
No, PCR duplicates only a small part of the DNA that is marked by the specific primers chosen
What is pleiotropy?
The ability of one gene influencing many characteristics (ex. sickle cell - one mutation creates many physical changes)
What is gene therapy?
The alteration of a person's genes in order to treat a disease
What is gel electrophoresis?
The analysis of an STR sample after being prepared by PCR; it allows visualization of DNA samples based on their lengths
If you were to compare a nucleotide from your DNA to a random one extracted from a bacterium, which components would be exactly the same and which might differ?
The backbone (sugar and phosphate) will always be identical, but the bases might differ
What is the cell theory?
The cell theory states that all life is cellular, and that all cells arise from preexisting cells
What is the key feature of Meiosis I with respect to the arrangement of chromosomes?
The chromosomes line up by homologous pairs (rather than singly, as they do in mitosis and meiosis II)
What is asexual reproduction?
The creation of a new individual by a lone parent without participation of sperm and egg
What is crossing over?
The process that produces hybrid chromosomes that are partially paternal and partially maternal; occurs during metaphase when homologous chromosomes line up during meiosis
What are exons?
The regions that do code for amino acids
What happens within the cytoplasm during translation?
The ribosomes read each successive codon and attach the proper amino acid to a growing chain
What is genomics?
The scientific study of genomes and their interactions
What are ribosomes?
The sites where proteins are made
What two parts of the DNA nucleotide are identical?
The sugar and phosphate
How are the sugars in DNA and RNA different?
The sugar in DNA is deoxyribose; the sugar in RNA is ribose. The sugar in DNA is missing one oxygen ('deoxy' means 'without an oxygen') compared to the sugar in RNA
What are induced mutations?
result from contact with environmental agents that alter DNA structure (mutagens)
What does the cleavage furrow consist of?
ring of protein filaments in the cytoplasm just under the plasma membrane
What does STR stand for?
short tandem repeats
What are the two types of nucleic acids?
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
What are the four bases of a nucleotide?
A - Adenine T - Thymine C - Cytosine G - Guanine
What is recombinant DNA?
A DNA molecule containing nucleotides from more than one source
What are codons?
A molecule of mRNA contains successive codons, which are sequences of three nucleotides, each of which specifies one amino acid
What is the machine called that the DNA sample is subjected to rounds of heating and cooling in?
A thermal cycler
What are nuclear pores?
Protein-lined; allow certain molecules, such as RNA, to pass through the nuclear membrane
What are restriction enzymes?
Proteins that cut DNA only at specific nucleotide sequences
How does cytokinesis occur in plant cells?
plant cells divide their cytoplasm by forming a cell plate
What does cells division have a role in?
reproduction, growth, and development
What are vesicles?
Small bubbles made of membrane that are used to transport materials through the cell
What does the semi-conservative property of DNA replication reveal?
The process of heredity
What does it mean to be a carrier?
You are a heterozygous individual -carriers do not have the disease, but they may pass it on to their offspring
What is DNA polymerase?
A naturally occurring enzyme that synthesizes a new DNA sample
What are somatic cells?
All of the body cells other than the reproductive gametes; they are diploid (only gametes are haploid)
What is chromatin?
the DNA and the protein that form a package
What are genes?
units of hereditary information
What are three cancer treatments?
"slash, burn, and poison" -first strategy is debulking by removing as much as possible -second step it radiation or chemotherapy
What are some genetic diseases that are chromosomal abnormalties?
-Edwards syndrome (trisomy 18) -Patau syndrome (trisomy 13) --Most infants don't live past their first week -Down Syndrome (trisomy 21)
What are relative causes of cancers (percents)
-Environmental - 70-80% -Smoking - 30-40% -Diet - 20-30% -Viruses - 5% -Hereditary factors - 10-20%
What is the accuracy in DNA profiling?
-1 in 10,000,000,000 to 1 in 1,000,000,000,000 -DNA profiles are reliable enough to be considered unique to each person who has ever lived -Non-coding regions!!
What and how many bonds between the nitrogenous bases?
-Adenine + Thymine = 2 hydrogen bonds -Guanine + Cytosine = 3 hydrogen bonds
What are the four nitrogenous bases? Which pair together?
-Adenine <3 Thymine -Guanine <3 Cytosine
Cancer statistics (amount of deaths, how common, social class, preventable)
-Cancer accounts for 7.4 million deaths worldwide -1 in 3 people will develop cancer during their lifetimes -70% of all cancer deaths occur in low and middle income countries -Over 30% of cancers are preventable
What are the reaction ingredients of PCR?
-DNA sample -Primers - short segments of DNA to "prime" the reaction -DNA polymerase to amplify DNA -Nucleotides to generate strands of DNA
What makes DNA a great molecule for inheritance? (genes to be passed on)
-DNA strands are complementary -to replicate, the DNA molecule is unzipped -each strand serves as a template to build a new strand -genetic instructions are passed down via DNA replication
What are some chromosomal abnormalities?
-Edward's syndrome (trisomy 18) -Patau syndrome (trisomy 13) --Most infants don't live past their first week -Down Syndrome (trisomy 21)
What are point mutations in sickle cell anemia?
-GAG -> mutation of GTG -when the RNA is produces, the bases become GAG without the mutation and GUG with the mutation -the mutated RNA then produces a mutant protein while the non-mutated DNA produces a normal protein
What role should DNA play in the criminal justice process?
-Innocence project -freeing 300 innocent exonerations
What happens in meiosis 1?
-Interphase --Chromosomes (uncondensed in this phase) replicate in preparation for meiosis -Prophase I --Replicated chromosomes condense --Spindle is formed --Homologous pairs of sister chromatids come together and cross over (randomly) --Nuclear membrane disintegrates -Metaphase II --Homologues move toward the center of the cell (at this point (referred to as the metaphase plate) and line up -Anaphase I --Homologues separate and are pulled to opposite poles. Sister chromatids going to each side are a mix of maternal and paternal genetic material
Mitosis vs. Meiosis?
-Mitosis produces the cells that build the human body and cell divisions allow an organism to grow and develop, repair tissues, and regenerate lost body parts -meiosis: A fertilized egg, or zygote, divides by mitosis. The fetus grows and develops into a mature adult consisting of countless somatic cells with identical DNA Each mature individual produces sex cells (gametes) by another form of cell division called meiosis
How do messages work with insulin? How do diabetes (1+2) work?
-Muscle cells receive the signal and take up glucose from your blood after eating sugar --Individuals that are Type 1 diabetic cannot make insulin and need to take insulin after a meal --Individuals that are Type 2 diabetic see the insulin, but their cells do not respond to it
What happens in normal meiosis?
-Ovary cell and testes cell (46 chromosomes) create egg and sperm with 23 chromosomes -After fertilization, a zygote is created with 46 chromosomes and develops into a normal individual
What happens in nondisjunction?
-Ovary cell and testes cell (46 chromosomes) go through nondisjunction and therefore the egg has either one extra or one fewer (22) chromosomes than normal; the sperm still has 23 chromosomes --After fertilization, the zygote has either one extra (47) or one fewer (45) chromosomes than normal; this produces an individual with an abnormal number of chromosomes; may result in death or abnormal features
How might genes have multiple effects?
-Polygenic inheritance is the effect of many genes on a single character --Many genes → polygenic inheritance → single character (e.g. human height)
What happens in Meiosis 2?
-Prophase II --Chromosomes in daughter cells condense --Spindle forms -Metaphase II --Sister chromatid pairs line up at the center of the cell -Anaphase II --Sister chromatids are pulled apart by the spindle fibers toward opposite cell poles -Telophase II and Cytokinesis --The nuclear membrane reassembles around the chromosomes --The two daughter cells pinch into four haploid daughter cells with 23 chromosomes each
What are the three major differences between DNA and RNA?
-RNA is single-stranded (not a helix) -sugar in RNA is ribose -the Thymine (T) is replaced by Uracil (U)
What is translation?
-Reading messenger RNA -triplet codons - select for specific amino acids
What is Turner Syndrome?
-Sex chromosomes: XO -Occurs in females -Symptoms: sterile; immature sex organs --Turner Syndrome is the only syndrome where having 45 chromosomes is not fatal
What is triple-X syndrome?
-Sex chromosomes: XXX -Occurs in the female -Symptoms: slightly taller than average; slight risk of learning delays
What is Jacob's syndrome?
-Sex chromosomes: XXY -Occurs in males -Symptoms: normal individual, but may be slightly taller than average
What is Klinefelter syndrome?
-Sex chromosomes: XXY -Occurs in males -Symptoms: sterile; underdeveloped testes; some feminine features
What are some genetic diseases that are single gene inherited?
-Sickle cell -Cystic Fibrosis -Huntington's Diseases
how do signals from other cells regulate genes in the receiving cell?
-Signal molecule from another cell → gene regulation → new protein made -Signaling molecules are constantly initiating some process for your body to respond
What are the hallmarks of cancer?
-Sustaining proliferative signaling -Evading growth suppressors -Activating invasion and metastasis -Enabling replicative immortality -Inducing angiogenesis -Resisting cell death
What is immunotherapy?
-T cell is a key fighter in your immune system -CAR is a specific receptor added to your T Cell -put together a CAR T CELL is created --they help to find and fight specific cells
How does pleiotropy refer to sickle cell anemia?
-The allele for sickle-cell disease is pleiotropic, influencing multiple traits
What is a tumor?
-a mass of body cells that is growing out of control -cell loses ability to control cell cycle
what is a proto-oncogene?
-a normal, necessary gene that produces a protein that properly regulates the cell cycle - cells are produced at the proper place and time
What is RNA?
-a nucleic acid -Ribonucleic Acid
What is hemophilia?
-an example of a recessive mutation on the X-chromosome -mostly effects males because for females both X chromosomes must be effected
What is a mutation?
-any change to the genetic information of a cell or virus -spontaneous change in DNA
What is a benign tumor?
-clean boundary between tumor and tissues -remains at the original site
What is the difference between coding and non-coding regions in DNA?
-coding DNA region makes protein -non-coding DNA region does NOT make protein
What does the nucleus contain and was it is surrounded by?
-contains most of the cell's DNA stored in chromosomes -surrounded by an envelop containing DNA, directs the activities of the cell
What is incomplete dominance?
-genes that show an intermediate phenotype -heterozygous individuals show an intermediate trait
The Immortal Life of Henriett Lacks, who was she?
-had cervical cancer caused by the virus HPV that has viral genes that lead to lod of cell cycle control -kept her cells in a lab in order to study them and produced cancer treatments
What are ways to prevent cancer?
-healthy diet -exercise -regular screenings -sun protection -not smoking -HPV vaccination protects against cervical, ana, prostate, and oral cancers
How does polymerase chain reaction copy target DNA quickly and precisely?
-heating splits apart DNA helix into complementary strands -cooling allows a heat-stable protein (DNA polymerase) to build new strands -using PCR, one drop of blood can provide enough DNA for analysis
What are alleles?
-individuals units of inheritance -alternate forms of a particular gene
What is a malignant tumor?
-invade surrounding tissues -migrate into other tissues = metastasis
What is sickle cell anemia?
-mutated hemoglobin forms strands that cause sickle shape -changing ONE nucleotide mutates protein -It causes red blood cells to form an unusual sickled shape, and it also provides resistance to malaria
What is an oncogene?
-mutated proto-oncogene that produces an abnormal protein that fails to regulate the cell cycle that results in a out-of-control cell growth -cells are produces continuously, not they and where they should be
Difference between normal tumor suppressor and mutated tumor suppressor?
-normal produces normal tumor suppressor and then regulates cell growth -mutated produces abnormal protein and then fails to stop the cell cycle leading to uncontrollable cell division
What are the molecules of DNA?
-nucleic acids -phosphate groups** -deoxyribose sugar** -nitrogenous base**
How do errors on proofreading lead to mutations? How do they try to remove incorrect nucleotides?
-polymerase adds incorrect nucleotides to the new strand of DNA -polymerase detects that bases are mispaired -polymerase uses 3' and 5' exonuclease activity to remove incorrect nucleotides
How do cells function as biological factories?
-provide structure and support -import nutrients and export cellular products -produce energy -create metabolic reactions -aid in reproduction -facilitate growth through cell division (mitosis)
what is the cell cycle control system? What does it consist of?
-regulates the timing of cell duplication -proteins that integrate information from the environment and communicate "start" and "stop" signals to the nucleus
What are eukaryotic characteristics?
-relatively large -more complex -surrounded by a plasma membrane -plant cells have an outer cell wall -cytoplasm: fluid-filled region between the plasma membrane and nucleus -organelles: "little organs" that perform specific functions -nucleus!! DNA storage
What are primers?
-short segments of DNA that act as the starting point for DNA synthesis - DNA polymerase is an enzyme (protein) that synthesizes DNA
What is CRISPR?
-system for editing DNA with a great deal of precision and efficiency -enables researched to modify almost any gene in any organism -naturally occurs in almost half of all bacteria as a mechanism ford recording encounters with viral DNA and using that information to protect against future infection
What is transcription?
-takes double-stranded DNA and converts it to single-stranded DNA -Thymine is replaced with Uracil
What is semi-conservative replication?
-the new DNA molecules are made up of one of the original parental strands plus a new strand -one original and the newly synthesized strand created from a template
What is nuclear transplantation?
-the nucleus is removed from an adult donor cell, injected into a nucleus-free egg cell, and then induced to grow into an embryo that may give rise to a whole organism - the resulting individual will be a clone of the animal that provided the adult cell nucleus
What is meiosis important for?
-the production of gametes by two rounds of cell division -egg sperm -duplication during interphase → meiosis I → meiosis II
What is nondisjection?
-when the chromosomes fail to separate properly after metaphase so the resulting gametes will have too few or too many chromosomes
How many crossover events tend to create a typical human chromosome?
1 to 2
How does CRISPR work?
1. After identifying a particular DNA sequence of interest, researchers synthesize an RNA "guide" molecule with a sequence that matches the target gene to be slices 2. the sequence for CRISPR RNA and Cas9 enzyme are introduced to the target cell using a plasmid 3. With the cell, the RNA leads the Cas9 enzyme to exactly the desired location of DNA, ad the Cas9 cuts the DNA there 4. At the location where the DNA is cut, a sequence can be inserted that repairs or alters the host cell's DNA
What are the three steps of DNA Replication?
1. Double helix is pulled apart 2. New strands are synthesized 3. DNA fragments are fused together
What are the three steps of translation?
1. Initiation (Ribosome assembles) 2. Elongation (Polypeptide grows longer) 3. Termination (Ribosome disassembles)
What are the four steps of transcription?
1. RNA polymerase binds a promoter 2. RNA polymerase synthesizes a molecule of RNA 3. RNA is spliced 4. The mRNA leaves the nucleus
What is the process of transcription
1. during transcription, the DNA double helix separates 2. one strand of DNA us used to generate a molecule of RNA 3. the RNA is processed to become messenger RNA, which then exits the nucleus via a nuclear pore
What are the steps of translation?
1. translation begins with two subunits that match the codon in mRNA 2. a tRNA brings in amino acids that match the codon in the mRNA 3. the completed polypeptide is not available to be used or modified by the cell into a functioning protein
What percent of human DNA encodes for proteins?
1.5%
By how much does meiosis reduce the genome by?
1/2
If an mRNA contains 300 nucleotides (not including the start and stop codons), how many amino acids does it encode
100 (3 mRNA nucleotides = 1 amino acid)
Each one of your cells contains instructions for building over ______________ different kinds of protein.
100,000
How many cells does an adult human have?
37.2 trillion
How many chromosomes do living cells contain?
46
How many individual pieces of DNA are in the nucleus of each of your body cells?
46, one long piece of DNA at each chromosome
In a study of mice, it was found that a molecule of mRNA lasts an average of how long within a cell?
9 hours
What percent identical are the genomes of two humans of the same sex?
99.5%
What is incomplete dominance?
A blending of traits. Red+White=Pink.
What is the endometrium?
A blood-rich layer of tissue that nourishes a developing embryo or is shed during menstruation
What are the three parts of each nucleotide?
A central five-carbon sugar (called deoxyribose in DNA), a negatively charged phosphate, and a base made from one or two rings of nitrogen and carbon
What is a genomic library?
A collection of DNA fragments that includes an organism's entire genome
What is STR analysis?
A comparison of the lengths of short tandem repeat sequences at 13 predefined sites within the human genome
How is the continuity of life maintained?
A complete set of genetic instructions must pass from one generation to the next
What is a genome?
A complete set of genetic material of an organism or virus?
What is the nuclear envelope/membrane?
A double phospholipid membrane that surrounds the nucleus; controls the passage of materials in and out of the nucleus
How do we produce large quantities of a desired human protein?
A gene that synthesizes the wanted protein is isolated and inserted into a piece of bacterial DNA called a plasmid. As the bacteria multiple, large amounts of the gene, and thus the protein, are produced.
What is a polymerase chain reaction (PCR)?
A laboratory technique by which a specific segment of DNA can be targeted and copied quickly and precisely (DNA IS DOUBLED)
What is the nucleolus?
A location within the nucleus where DNA from multiple chromosomes directs the production of a kind of RNA called ribosomal RNA (rRNA). They exit through the nuclear pores and enter the cytoplasm, where they join together with protein molecules to form a ribosome (the cell structure that manufactures proteins)
What is a polynucleotide?
A long strand of individual nucleotides
What is induction?
A mechanism that occurs when one group of cells influences the development of an adjacent group of cells (can cause cells to change shape, destroy other cells, migrate, etc.)
What is a nucleic acid probe?
A molecule made using radioactive or fluorescent building blocks
What is the endoplasmic reticulum?
A network of membrane-enclosed passageways and sacs that touches the outside of the nuclear envelope and extends deep into the cytoplasm
What happens if someone is missing an autosome?
A person missing one sex chromosome can live a normal life, but missing an autosome is inevitably fatal
What is a karyotype?
A photographic inventory of the chromosomes in one person's cells
What does a researcher use to copy that region?
A primer - short (usually 15 to 20 nucleotides long) single-stranded DNA molecules with sequences that are complementary to sequences at each end of the target sequence
What is X chromosome inactivation?
A process when one of the X chromosomes in each body cell is highly compacted and almost entirely inactive; males and females have the same number of active X genes
What is Cas9?
A protein that cuts DNA at locations that are complementary to a molecule of guide RNA; it's like a guided missile, with an RNA molecule as the guidance system
How is Cas9 involved in the alteration of a mutated cell?
A scientist injects the Cas9 protein and its attached guide RNA. The guide RNA is complementary to a target DNA sequence, such as a gene. After Cas9 cuts the target sequence, DNA repair enzymes fix the gap. In this way, the CRISPR-Cas9 system acts like the "search and replace" function of a word processor, potentially fixing mutations in cells
What is cleavage?
A series of rapid divisions that continue for days (starting about 36 hours after fertilization); zygote becomes embryo after first division
What is the golgi apparatus?
A series of sacs where proteins are modified, stored, and distributed after being produced at ribosomes and traveling through the cytoplasm
What is DNA profiling?
A set of laboratory techniques that allows an investigator to determine with certainty whether two samples of DNA came from the same individual
What is DNA technology?
A set of methods for studying and manipulating genetic material; DNA technology has become increasingly important to our society since it was first developed in the 1970s
What is the whole-genome shotgun method?
A set of several techniques used to sequence an entire genome; DNA is obtained -> DNA is cut up by restriction enzymes -> the sequence of DNA fragments is determined by an automated sequencing machine -> computer programs use overlapping regions from each fragment to determine the original order of the sequences -> the complete genome is uploaded to a database
What is a haploid?
A single set of chromosomes for each gamete (represented as n)
What is a restriction site?
A specific DNA sequence recognized by a particular restriction enzyme
If you examine a human cell and observe that it has 23 chromosomes including one Y chromosome, where must it be from?
A sperm cell, since it is haploid and has a Y chromosome
What is the CRISPR-Cas9 system?
A technology that allows the nucleotide sequence of specific genes to be edited in living cells
Explain the fourth step of transcription (The mRNA leaves the nucleus)
After processing, the finalized messenger RNA molecule leaves the nucleus from an opening in the nuclear membrane called a nuclear pore. In the cytoplasm, the molecule of mRNA will be used as instructions for generating a protein.
What is random fertilization?
An egg will be released but the body does not know what specific genotype it will be; body releasing sperm - one will randomly fertilize that egg
What leads to the development of complementary DNA?
An enzyme called reverse transcriptase can synthesize DNA molecules from the collection of mRNAs within the cell; complementary DNA represents just the genes that were producing proteins in the cell at that time
What are some structural similarities between DNA and RNA?
Both are nucleic acids, polymers of nucleotides; each of which consists of a sugar, phosphate, and a base
What is the second step of Meiosis II?
Chromosomes separate. The sister chromatids split apart, with one copy distributed to each side of the cell (anaphase II)
What is a character?
An inherited feature that varies from one individual to another
What is a transgenic organism?
An organism with a transferred gene from another species (for example, a goat carrying a gene from a human)
What is a whole genome?
An organism's entire set of DNA (about 3 billion nucleotides in humans)
How is mRNA read?
As a series of triplet codons (9 nucleotides)
What are carcinogens?
Cancer-causing agents; agents in the environment that in most cases (not all) promote the development of cancer
What is the most common type of mutagen?
Carcinogens
What does CRISPR stand for?
Clustered Regularly Interspaced Short Palindromic Repeats
Why can no two humans (with the exception of identical twins) have the same number of repeats at all 13 STR sites?
At each site, a four-nucleotide sequence is repeated between 3 and 50 times in a row. The sites vary so widely, that it's impossible to have the same number of repeats at ALL 13.
Explain the first step of translation (Initiation)
At first, the ribosome exists as two separate components; the large and small subunits. Translation begins when an mRNA molecule binds to a small ribosomal subunit. A molecule of transfer RNA (tRNA) then binds to the start codon of the mRNA, where translation is to begin. This first tRNA carries the amino acid methionine (Met); its anticodon, UAC, binds to the start codon, AUG. Next, a large ribosomal subunit binds to the small one, creating a complete ribosome.
What is the third step of Meiosis II (Cytokinesis)?
At the end of Meiosis II, each cell splits by cytokinesis, producing a total of four offspring cells, each with half the number of chromosomes as the starting cell. The nuclear membranes re-form, and the chromosomes uncondense (telophase II)
How can we reduce the risk of developing cancer?
Avoiding mutagens - using sunscreen, not smoking, avoiding a high-fat diet, etc.
Why do nonsense mutations often have a strong effect?
Because an amino acid codon is changed to a stop codon, resulting in a shortened (and therefore probably defective) protein
How is transcription and translation different in bacteria?
Because bacteria lack nuclei, transcription and translation occur at the same place and time.
If a DNA molecule is chemically modified to glow and then replicated with non-glowing nucleotides, will either neither, or both of the two new molecules glow?
Because each new DNA molecule receives half of the original, both will glow (but half as brightly)
What does the nucleic acid probe do?
Because it has a sequence that matches the desired target (by following the base-pairing rules), the probe will bind to and help visualize the target DNA
From a cell division perspective, why are all of the trillions of cells in your body genetically identical?
Because they all descended via cell division from a single original cell (the zygote)
What does each ribosome contain?
Binding sites for the mRNA as well as for molecules of transfer RNA (tRNA)
What is a major similarity in the production of genetically modified plants and mammals?
Both use a plasmid to introduce foreign DNA
How are genetically modified food crops produced?
By inserting a desired gene into a plasmid, a small, circular, independently replicating piece of DNA originally isolated from a bacterium. The plasmid acts as a temporary DNA carrier, allowing a gene of interest to be inserted into the genome of a plant. The result is a genetically modified plant that expresses the trait from the newly inserted gene
How is the cutting and pasting of DNA achieved?
By using restriction enzymes
What are some multifactorial inherited diseases?
Cancer Diabetes Alzheimer's
What is the second step of Meiosis I?
Chromosome pairs separate (anaphase I), with each member of a pair heading to the opposite ends of the cell. Each chromosome still consists of two joined sister chromatids
What is the first step of Meiosis I?
Chromosomes condense and line up by pairs
What is the first step of Meiosis II?
Chromosomes condense and line up. In each of the two cells produced by Meiosis I, the chromosomes (still duplicated, with sister chromatids attached at a centromere) condense (prophase II) and line up singly in the center of the cell (metaphase II)
What happens during interphase?
Chromosomes duplicate. Before meiosis begins, the chromosomes are duplicated within the nucleus. These chromosomes are homologous pairs - one derived from the mother and the other from the father
What happens during Metaphase I?
Chromosomes line up by homologous pairs along the center line of the cell (during this stage, aligned chromosomes may swap pieces with each other)
What molecule holds the instructions for all living things?
DNA
What is the method called for producing multiple identical copies of a piece of DNA?
DNA cloning
How are proteins made?
DNA directs production of RNA which directs production of protein
What is the flow of genetic information?
DNA directs the production of RNA, which in turn controls the manufacture of proteins. Proteins then perform the majority of cellular functions. It is through these processes that DNA controls your physical traits
How does DNA make brown eyes?
DNA holds information on how to produce proteins
Where does the flow of information in a cell start?
DNA in the nucleus
How is an STR analysis performed?
DNA is obtained from two or more samples and then the polymerase chain reaction produces large quantities for comparison
What is the difference in number of strands between DNA and RNA?
DNA is often double-stranded while RNA is usually single-stranded
What enzyme pastes together the fragments of DNA during the production of protein in a large quantity?
DNA ligase
What is DNA polymerase used for in the coping of DNA in PCR?
DNA polymerase can bind the primers and synthesize new DNA molecules using free nucleotides included in the mixture. This creates a large sample of DNA that can be used for further experiments
Explain the third step of DNA replication
DNA polymerase creates the new DNA molecule in fragments. An enzyme called DNA ligase joins the individual fragments, fusing them together into the final DNA molecule.
Explain the first step of DNA replication
DNA replication begins when an enzyme called helicase attaches to specific DNA sequences called origins of replication. Starting at that point, the enzyme peels apart the two DNA strands of the double helix from each other, forming a replication bubble. Because the double helix is peeled apart, the bases in each separated DNA strand within the replication bubble are now exposed.
What do biologists use PCR to do?
Determine DNA profiles, study relationships among organisms, and to hunt for disease-causing genes
What process involves frequent cell division?
Development
What is built during translation?
During the process of translation, the sequence of RNA nucleotides in a molecule of mRNA provides instructions to build a sequence of amino acids.
Explain the second step of DNA replication
Each of the two separated DNA strands is bound by an enzyme called DNA polymerase. This enzyme builds a new DNA molecule that is complementary to the existing strand. DNA polymerase matches up a correct free nucleotide with the separated strand (A with T, etc.) This happens to both peeled-apart DNA strands simultaneously, with each original DNA strand serving as a template to build a new complementary DNA strand
Explain the third step of translation (termination)
Elongation continues until the ribosome reaches a stop codon on the mRNA. Stop codons - UAA, UAG, and UGA - do not code for amino acids but instead indicate that translation should cease. The completed polypeptide, typically several hundred amino acids long, is freed. The ribosome splits back into its subunits, releasing the mRNA and tRNAs. The released mRNA may then begin another round of translation, producing another protein
What does the membrane of the smooth ER contain?
Enzymes that produce lipids, such as steroid hormones
What is an example of a genetic characteristic that is controlled by one gene?
freckles - dominant gene
What is one example of a carcinogen?
Exposure to UV radiation in sunlight can cause mutations that lead to melanoma (skin cancer)
What is chromatin?
Fibers formed by DNA molecules wrapped around proteins; chromatin twists and folds to create a chromosome
What are sticky ends?
Fragments with just single stranded regions; they can then join to other pieces of DNA with complementary DNA sequences
What are linked genes?
Genes that are located near each other on a chromosome and therefore tend to be inherited together; represents an exception to the law of independent assortment
What are GMOs?
Genetically modified organisms; ones that have acquired one or more genes by artificial means
What is the purpose of the DNA molecule undergoing heating and cooling?
Heating causes the hydrogen bonds that hold together the double helix to break apart, and cooling allows the hydrogen bonds to re-form
What was the world's first genetically engineered pharmaceutical product?
Humulin (human insulin produced by bacteria)
What is located in the center of the double helix?
Hydrogen bonds between bases that hold the two strands together
Why might a molecule of mRNA be shorter than the gene from which it is derived?
If introns are removed, the mRNA would be shorter
How could the duplication of a gene result in cancer?
If that gene produces a growth factor, duplication of the gene may result in overstimulation of growth
How are the bases related between DNA and RNA?
In DNA, the bases are adenine, thymine, cytosine, and guanine. In RNA, Uracil replaces Thymine
Explain the third step of transcription (RNA is spliced)
In a eukaryotic cell, the molecule of RNA that is produced during transcription is processed before it leaves the nucleus. Introns are removed, and exons are joined together. In some cases, one RNA molecule may be spliced in multiple ways, resulting is several different proteins from one gene. In addition to splicing, extra nucleotides are added as a "cap" and "tail" to the RNA.
How fast is DNA replication?
In a living cell, DNA replication can proceed at a speed of about 50 nucleotides every second
Where does fertilization take place?
In the oviduct (fallopian tube)
What is each molecule of DNA made from?
Individual subunits called nucleotides
What are nucleic acids?
Information molecules that contain directions for the production of other molecules
How does gene therapy work?
It begins with the isolation of the normal gene from a healthy person. Enzymes produce an RNA version of the target DNA gene. This RNA gene is combined with an infectious retrovirus (a virus with an RNA genome). The retrovirus is usually a crippled version of a cold virus which infects, but does not cause harm to humans. The recombinant retrovirus is ready for therapy.
What happens after a molecule of RNA is synthesized during transcription?
It is altered in several ways before it departs the nucleus
What is the appearance of the rough ER?
It is studded with ribosomes attached to its surface that produce many different kinds of proteins
Why can the DNA polymerase used in PCR tolerate such high temperatures?
It was originally isolated from a prokaryote that lives in natural hot springs
What is a follice?
Located within the ovary; contains a single developing egg surrounded by cells that nourish it
What are homeotic genes?
Master control genes that produce protein signals and turn groups of other genes on and off; help establish the overall structure of an organism
What is gene regulation?
Mechanisms that turn on certain genes while keeping other genes turned off in a particular cell
Is biotechnology a recent development?
No. Although genetic engineering is only a few decades old, humans have been manipulating living organisms for thousands of years
Is a chromosome in one of your gametes likely to be just like one that you received from your parents?
No. Due to crossing over, most chromosomes in your gametes are hybrids with parts from both your maternal and paternal chromosomes
What is mRNA?
Messanger RNA; the molecule that results from transcription. However, during transcription, Uracil is used in RNA instead of Thymine. After it's made, mRNA exists the nucleus and travels to the ribosome for translation
Which animal organelle is involved in energy production? Which plant organelle?
Mitochondria in animal cells; mitochondria and chloroplasts in plant cells
What have CRISPR gene editing techniques been used to treat recently?
Muscular dystrophy in mice and dogs
What is the cervix?
Narrow opening between the uterus and vagina - baby passes through during birth
Can genes located on separate chromosomes be linked?
No
Do our chromosomes contain any Uracil bases?
No because our chromosomes are made up of DNA, not RNA.
Does PCR copy all of a DNA sample?
No, PCR is typically used to copy one specific region within the larger DNA molecule
Is it likely for a crossover to occur between linked genes?
No, crossovers separating two genes is related to how far apart those genes are on a chromosome.
Imagine all the cells in your body - your blood cells, brain cells, intestinal cells, etc. They are all genetically identical: they all have the same set of DNA. Do all your cells express the same gene?
No, since they don't all need to make the same proteins
Are we certain that GMOs are not dangerous or contain any negative effects?
No, there is still a lot we don't know about this new technology.
In one of your cells, could transcription and translation of one mRNA take place simultaneously?
No. Transcription takes place in the nucleus (where the DNA is), but translation occurs in the cytoplasm (where the ribosome is).
With respect to the number of chromosomes, is there any difference between a cell about to start mitosis and a cell about to start meiosis?
No; both have duplicated chromosomes
List the organelles involved in protein production in order, starting where the DNA is
Nucleus ER Ribosomes Vesicles Golgi Vesicles
What happens during transcription and where does it occur?
Once in the cytoplasm, the RNA molecule makes its way to a ribosome, where the message it contains is converted to protein through the process of translation.
Explain the second step of translation (elongation)
Once initiation is complete, additional amino acids are added one by one. The anticodon of an incoming tRNA molecule, carrying its amino acid, pairs with the mRNA codon via the RNA base-pairing rules. The new amino acid is added to the end of the growing polypeptide chain. The old, empty tRNA (the one that brought the amino acid during the previous step) exits the ribosome, and the ribosome moves the remaining tRNA to the spot just vacated, creating space for the next tRNA to enter. This process continues, with each entering tRNA bringing a new amino acid to be added.
How can one gene direct the production of several different kinds of proteins?
One gene may have several exons, which can be spliced together in many different ways to produce different proteins
Of the methods of contraception listed, which ones actually prevent gametes from being formed?
Only female oral contraceptives - prevent eggs from being formed and therefore sperm cannot fertilize
What was found through The Human Genome Project?
Our chromosomes (22 that we all share, plus the sex chromosome) contain about 21,000 genes within about 3 billion DNA nucleotides; since then, genomes of several organisms have been sequenced
What are mutagens?
Physical or chemical factors in the environment that can damage DNA
What two extensions of Mendelian genetics are essentially the opposite of each other?
Pleiotropy is one gene affecting many characters, whereas polygenic inheritance occurs when many genes affect a single character
What is responsible for your physical traits?
Proteins!
What is the purpose of RNA?
RNA carries instructions that result in the production of proteins. These proteins then perform the cellular work that is essential. to life
Considering that DNA never leaves the nucleus, why would it be detrimental to a cell's functioning if there were no nuclear pores, leaving the nucleus completely enclosed?
RNA must be able to exit the nucleus to carry messages from the DNA to the cytoplasm
How does the process of transcription begin?
RNA polymerase binds to a specific region of DNA
What is genetic information encoded into?
RNA that leaves the nucleus and then used to produce proteins by ribosomes in the cytoplasm
What is independent assortment?
Random distribution of homologous chromosomes when they line up in the middle of the cell; causes 8 million possible combinations of chromosomes that can be distributed to the gametes
After cutting at the restriction site, what are the left-over nucleotides called?
Restriction fragments
What do ribosomes use for the process of translation, and what purpose do they serve?
Ribosomes use information coded in mRNA polynucleotides created during the process of transcription to produce corresponding amino acid polypeptides
What happens in a stimulative faulty control system?
Signal for cell division is not present → hyperactive mutant relay protein → signal transduction → excessive cell division
What happens in a stimulative normal control system?
Signal for cell division is present → relay proteins, transduce signal → normal cell division Signal for cell division is not present → no signal transduction → no cell division
What happens in an inhibitive signaling normal control system?
Signal to inhibit division is present → Relay proteins transduce signal → cell division inhibited Inhibitory signal is absent → no signal transduction → cell not inhibited; cell divides
What happens in an inhibitive signaling faulty control system?
Signal to inhibit division is present → relay protein absent or nonfunctional → excessive cell division
What are short tandem repeats (STRs)?
Sites where a short nucleotide sequence is repeated many times in a row
What is genetic engineering?
The direct manipulation of genes for practical purposes, such as the production of pharmaceuticals; this often involves creating recombinant DNA, a segment of DNA containing sequences from two different sources
What is polygenic inheritance?
The effect of many genes on a single character (ex. human height and skin color)
How does the process of preparing recombinant DNA work?
The entire genome is cut up with restriction enzymes to create a large set of fragments. Each of these fragments can then be inserted into a separate plasmid (a small circular bit on bacterial DNA), producing a large set of plasmids, each of which contains one segment of DNA
What are proteomics?
The field that studies the complete set of proteins (proteins perform the tasks that keep cells functioning) encoded by a genome
What is gene expression?
The flow of genetic information from DNA to RNA to protein
What is sexual reproduction?
The formation of genetically unique offspring; begins with fertilization
What happens during and transcription and where does it occur?
The information in a DNA gene is converted to an RNA molecule through the process of transcription; this occurs in the nucleus. The RNA leaves the nucleus, exiting through an opening in the nuclear envelope called a nuclear pore.
What is fertilization?
The joining of gametes (sperm from father and egg from mother) to form a single cell
Are STRs identical from person to person?
The locations of these sites are identical, but the number of repeats varies widely within the human population
What is biotechnology?
The manipulation of organisms or their components to make useful products; biotechnology is as old as human civilization; prehistoric humans selectively bred livestock and used yeast to make bread
What molecule results from translation?
The molecule that. results, consisting of a string of amino acids, is called a polypeptide. After further modifications, the polypeptide can serve as a functioning protein
What is a blastocyst?
The name of the embryo when it is a fluid-filled ball of about 100 cells
What happens at the end of translation?
The newly formed polypeptide is released, and the ribosome disassembles back into its parts
What is the third step of Meiosis I (cytokinesis)?
The nuclear membrane begins to re-form (telophase I). As it does, the cell divides into two cells (cytokinesis). There are now two offspring cells, each with the haploid number of still duplicated chromosomes
What happens during Prophase I?
The nuclear membrane dissolves and chromosomes condense
Where does transcription occur in eukaryotic cells?
The nucleus
What is the result of only one set of chromosomes being passed down during asexual reproduction?
The offspring are genetically identical to each other and to the lone parent
How are the phosphate groups between DNA and RNA related?
The phosphate groups are identical
What is the definition of transcription?
The transfer of information from DNA to a molecule of messenger RNA (mRNA)
What is heredity?
The transmission of traits from one generation to the next
What is a codon?
Three consecutive nucleotides
What is one of the most important steps in any genetic engineering project?
To cut and paste specific pieces of DNA
What is the genomic library used for?
To hunt for and manipulate any gene from the starting organism
Why are viruses particularly good carriers of healthy human genes for therapy?
Viruses naturally infect human cells, making them well suited to insert the normal DNA into a patient with a disease
What are the two transformations the genetic information endures in the journey from DNA to RNA to protein?
Transcription and translation
Explain the first step of transcription (RNA polymerase binds a promoter)
Transcription begins when an enzyme called RNA polymerase binds to a DNA sequence called a promoter. The promoter acts as a "start here" signal, marking the beginning of a gene. By controlling whether or not RNA polymerase can bind the promoter, a cell can turn a gene on or off.
When does transcription end?
Transcription ends when RNA polymerase reaches a DNA "stop" sequence called a terminator. At this point, RNA polymerase detaches from the RNA molecule and the gene, and the original DNA molecule is restored.
How does translation begin?
Translation begins when ribosome parts assemble around a molecule of mRNA
What is a signal transduction pathway?
Triggered by molecules exiting cell and binding to a receptor protein on the outside of another cell; a series of relay molecules that convey the message from the outside of the cell into the cell's interior cytoplasm and nucleus (signal turns gene on or off)
Which of the syndromes is the one where having 45 chromosomes is not fatal?
Turner syndrome
How many polynucleotides are in one molecule of DNA?
Two
What are homologous chromosomes?
Two chromosomes in a matching pair; carry genes controlling the same inherited characteristics
What are traits?
Two or more variations of a character
What is a diploid?
Two sets of chromosomes contained in a zygote when the gametes fuse together (represented as 2n)
What is semi-conservative replication?
Two strands of an original DNA molecule separate from each other and serve as a template. Each new DNA molecule produced contains one newly created strand and one strand from the original molecule. It conserves half of the original molecule
What are examples of induced mutations?
Ultraviolet (UV) radiation that has smaller wavelengths and higher energy than visible light
What is infertility?
Unable to conceive a child despite one year of trying
How does the recombinant retrovirus that carrie the healthy gene get inside of a diseased person's cells?
Usually through bone marrow cells because they multiple continuously and can produce the normal protein for a long time (the goal is for a permanent cure with one injection)
What is RNA splicing?
When introns are removed and exons are then joined together
What are the sex chromosomes for females and males? (know how to distinguish for the exam)
XX female and XY male
Is the chemical structure of DNA the same as any other cell on Earth?
Yes
Is it possible for a female carrier to have a daughter who has hemophilia?
Yes, if she mates with a male who has hemophilia.
Can mutations involve more than just a single DNA nucleotide?
Yes, some mutations involve just a single DNA nucleotide, others affect a group of nucleotides, and some can even change a large region of a gene
If you produce a genomic library with all the genes in a human cell, how can you find the few bacteria that contain a particular gene?
You can use a probe that is complementary to the desired gene
What is the single cell formed from fertilization called?
Zygote
What is a carcinogen?
a cancer causing agent
What is cancer?
a disease of the cells - occurs when abnormal cells divide uncontrollably and invade nearby tissues --cancer cells ignore the tissue structure and grows on top of the sheet of cells
What does transcription create?
a molecule of RNA from a molecule of DNA
What does translation create?
a molecule of protein via the genetic code
What charge does the phosphate group have (-/+)?
a negative charge
What is a growth factor?
a protein that stimulates cell division
what is a cell plate?
a strip of membrane and cell wall materials that forms along the center line of the wall
Why do nonsense mutation often have a strong effect?
because an amino acid codon is changed to a stop codon, resulting in a shortened and therefore probably defective protein
How is your skin color determined?
both genetically and environmentally (sun exposure)
If a nucleus is removed from a brown mouse, injected into a nucleus-free egg from a white mouse, and the resulting embryo is implanted in a black mouse, what color will the babies be?
brown since that is the source of the nucleus
What is a pedigree?
can be used to track genetic traits in a family
What is interphase?
cell preforms its normal functions and duplicates the chromosomes
How does a cell send a message to other cells?
cell-to-cell signal → signal molecule → cell receiving the message --molecules exit one cell and bind to a receptor protein on the outside of another cell
How does cell division work for growth and development?
cells are rapidly dying and cell division produces a continuous supply of replacement cells
What does a missense mutation do?
change in individual base in DNA, but does not change amino acid
What does a silent mutation do?
change in individual base in DNA, but does not change amino acid
What is a nonsense mutation?
changes an amino acid codon that will produce a shortened protein that is almost always defective
What happens in S phase?
chromosomes are bing duplicated --46 chromosomes to 96
What are tumor-suppressor genes?
code for proteins that inhibit cell division
What does recombinant chromosomes mean?
contains parts from both original chromosomes
What is the final step of the cell cycle?
cytokinesis
How is UV radiation dangerous?
degrades folic acid, which in needed for DNA replication and repaid -UV light causes adjacent thymine and cytosine nucleotides to bind deforming DNA molecule (can lead to melanoma)
What is a silent mutation?
does not change the amino acid produced because some amino acids are encoded by more than one RNA sequence so the protein is unchanged
What is DNA?
double-stranded helical macromolecule consisting of nucleotide monomers with deoxyribose sugar, a phosphate group, and the nitrogenous bases
What happens during interphase?
each chromosome in a homologous pair replicates to form two sister chromatids
What are the products of meiosis?
four haploid cells, each containing just one copy of each chromosome, rather than a homologous pair --haploid daughter cells --one sex chromosome
Cancer can be inherited by an offspring from his or her parent only if the mutation occurs in the parents...
gametes (sex cells)
Which genes have the least likeliness of crossing over?
genes located near each other
What are tumor suppressors?
genes normally function to control cell growth
What is a genotype?
genetic alleles
What are the different components of a gene?
genetic and environmental (or both)
How is your blood type determined?
genetically determined
What are clones?
genetically identical individuals born of a single parent
What does a mutation in a growth factor gene lead to?
hyperactive protein that promotes unnecessary cell division
Where do mutations occur?
in coding (functional genes) and noncoding DNA
How are chromosomes organized on a karyotype?
in homologous pairs
Where do cells spend most of their lifetime?
in interphase - 90% of the cell cycle
Where are STR's located?
in non-coding regions so there is no evolutionary advantage to them (that we know of)
What happens in Meiosis 1?
in the first division of meiosis, the homologous pairs separate
Where are chromosomes found?
in the nucleus
What happens in Meiosis 2?
in the second division of meiosis, the sister chromatids seperate
How does a women being pregnant at an older age effect her child?
increases risk of down syndrome
What three major processed lead to variation in the norm for sexual reproduction?
independent assortment (meiosis) -crossing over (meiosis) -random fertilization (fertilization)
What are the three phases of translation?
initiation, elongation, termination
Where does the cell spend most of its lifetime?
interphase - 90% of the cell cycle
What are the two broad stages of the cell cycle?
interphase and mitotic phase
What is the effect of having a BRCA mutation?
it will dramatically increase your lifetime risk of developing breast and ovarian cancer --BRCA is the breast cancer susceptibility gene
What are some mishaps in meiosis?
nondisjunction -zygotes with an abnormal chromosomes number will usually not develop or will have abnormalities
What is a nonesense mutation?
leads to stop amino acid and the amino acid is not made
What is a chromosome?
long piece of DNA associated with proteins that help keep the DNA tightly organized in the nucleus
What are the leading types of cancer?
lung, stomach, collateral, liver, breast
How does RNA serve as instructions for making proteins?
mRNA → translation [ribosome] → polypeptide amino acid → protein
What is the goal of Polymerase Chain Reaction (PCR)?
make copies of DNA segments outside of the body - DNA replication in a test tuve
What is plant cloning?
many plants are propagated by placing small sampled, even individual cells, into growth liquid where the individual cells divide and develop into new plants
What is the cell cycle controlled by?
many proteins in signal cascades
What is a karyotype?
photographic inventories of chromosomes
What is the other 10% of a cells life?
mitosis
What are the two stages of the mitotic phase?
mitosis and cytokinesis
What causes tumors to form?
mutations in genes that normally regulate the cell cycle
What is chromosome duplication?
near the end of interphase the cell duplicates each chromosome and during the mitotic phase one copy of each chromosome is moved to each offspring cell
Do all genes obey Mendel's law of independent assortment?
no because linked genes located close together on the same chromosome and tend to be inherited together
What is a phenotype?
observable trait → physical
What does pleiotropy refer to?
one gene, many effects
What does a punnett square allow you to do?
predict the genotype and phenotype of your offspring
What is G2?
preparation for mitosis - cytoplasm and organelles are duplicated during this phase
What is apoptosis?
programmed cell death --carves out distinctive structures --weeds out aging and/or defective cells
What are the stages of mitosis?
prophase, metaphase, anaphase, telophase
What are DNA molecules wrapped around?
proteins to form fibers called chromatin (each very long chromatin twists and folds to form a chromosome)
What are different types of mutations?
replacing, deleting, or adding a nucleotide base and can have a wide range of effects
What are the three types of point mutations?
silent, missense, nonsense
How does gel electrophoresis work?
sorts DNA fragments by size
What is therapeutic cloning?
stem cells are harvested from cloned embryo
What is a missense mutation?
substitution of one amino acid for another which produces a mutant protein which may be nearly identical to or substantially different from the original
Which chromosome is required to live?
the X chromosome
what is the mitotic phase?
the cell divides the nucleus and distributes the duplicated chromosomes into new cells
What happens in G1?
the cell is taking inventory
What happens to the cell plate in cytokinesis?
the cell plate builds up and eventually fuses with the plasma membrane, separating the two offspring
Explain why the following statement is incorrect: "during mitosis chromosomes are duplicated and distributed."
the chromosomes are already duplicated by the time the mitotic phase starts --> they are duplicated during interphase
what is cytokinesis?
the cytoplasm is divided and distributed
What is cytokinesis?
the distribution of the cytoplasm to the two offspring cells --proceeds differently in plant and animal cells
what is mitosis?
the nucleus, along with its already duplicated chromosomes, divides and is distributed to the two offspring cells
What is the cetromere?
the region of a chromosome where the two sister chromatids are joined together
What happens when a tumor-suppressor gene is mutated?
the resulting protein may fail to stop the cell cycle
What happens if a growth factor is mutated?
the resulting protein may promote cell division even when it is not appropriate
What is metastasis?
the spread of cancer cells beyond their original site
What are point mutations?
the substitution of one DNA nucleotide for another
How does cytokinesis occur in animal cells?
through the process of cleavage - first sign of this is cleavage furrow that created an indentation around the equator of the cell - eventually the parent cell is pinched in two leaving two independent offspring cells
Which of the two is inherited: tumor suppressor or oncogene?
tumor suppressor
What does uncontrolled cell division result in?
tumors
What is heterozygous?
two different alleles (Hh)
what is the result of the mitotic phase?
two genetically identical offspring cells that then begin their own cell cycles
What is homozygous?
two identical alleles (HH or hh)
What are sister chromatids?
two identical parts of a duplicated chromosome that when joined two sisters join together they become a chromosome
What does the process of cell division produce?
used for the body for growth, repair, and reproduciton
What is DNA replication?
when a cell duplicates its chromosomes
what is cancer
when the tumor spreads spreads to other tissues